Study compares treatments for chronic plaque psoriasis

Oral psoralen - UV-A therapy was found to be more effective than narrowband UV-B therapy in treating patients with chronic plaque psoriasis, according to an article in the July issue of Archives of Dermatology.

It is unclear whether narrowband UV-B (NB-UVB) therapy is as effective as psoralen-UV-A (PUVA) therapy in treating psoriasis, according to background information in the article. PUVA therapy includes the combination of 8-methoxypsoralen medication (taken orally) and exposure to UV-A (long-wave) radiation. NB-UVB involves exposure to UV-B (short-wave) radiation and is thought to be safer than PUVA.

Sami S. Yones, M.Sc., and colleagues from King's College London conducted a randomized, double-blind trial comparing the efficacy of PUVA and NB-UVB therapies in treating chronic plaque psoriasis. Ninety-three patients with moderate-to-severe cases of the disease were recruited to participate in the study. Two hours before receiving UV treatment, patients in the NB-UVB group took a placebo and those in the PUVA group took 10-mg of 8-methoxypsoralen. Patients in both groups attended sessions twice weekly until their skin cleared, up to a maximum of 30 sessions. Patients whose skin cleared were followed up until relapse or for 12 months.

In patients with skin types I through IV (skin more likely to burn), PUVA was more effective than NB-UVB at clearing skin, with respective 84 percent vs. 65 percent clearance. Patients in the PUVA group also achieved skin clearance in a significantly shorter number of treatments, a median of 17 treatments, compared to 28.5 treatments in the NB-UVB group. Nearly half of patients in the PUVA group experienced erythema (redness of the skin) at some point during treatment, compared to less than one-quarter in the NB-UVB group. Six months after skin clearance was achieved, 68 percent of patients in the PUVA group were still clear compared to 35 percent of patients in the NB-UVB group. Overall, patients with skin types V and VI had a lower rate of clearance than those with skin types I through IV (24 percent vs. 75 percent).

The authors write that despite the disadvantages of PUVA treatment (i.e., may cause nausea, has the potential to cause skin cancer, cannot be used during pregnancy), their results "suggest that PUVA compared with NB-UVB tends to clear psoriasis more reliably, with fewer treatments and for longer and should, therefore, still be used in appropriate patients."